1. Field of the Invention
The invention relates to a rotor blade, in particular of a main rotor of a rotary-wing aircraft or helicopter, made of fibre-reinforced plastic. This comprises a blade section and a connecting section for fastening the rotor blade to a drive device. The connecting section comprises a sleeve-shaped connecting device and lies at the end of the rotor blade opposite to the blade tip and therefore facing a drive axis. It connects the rotor blade at least indirectly to the drive device. For this it comprises at least one sleeve-shaped connecting device, for example, for a bolt connection. The rotor blade more favourably has two sleeve-shaped connecting devices which are disposed adjacent to one another in the plane of rotation of the blade since tilting moments of the blade from its forward travel or as a result of its inertia can be absorbed.
2. Description of Related Art
Nowadays rotor blades are usually manufactured using the wet or prepreg method of construction. This offers a low degree of automation and is associated with a large amount of manual work and is as a result very cost-intensive and liable to error. Even small improvements of the rotor blade or its method of manufacture can therefore have a cost-reducing or quality-enhancing effect. The development of new rotor blade systems is primarily directed towards reducing the power requirement, the weight and the maintenance expenditure as well as towards increasing the lifetime and reducing the manufacturing costs. The lifetime is substantially determined by the introduction of forces and the transmission of forces between the rotor blade and the drive device. The introduction of forces into the rotor blade is usually effected via loop and bolt connections which are dynamically highly loaded. Loop connections are regarded as solutions appropriate to fibres. It is found, however, that their operating strength is determined by the resin properties. As a result, additional structural-2-elements can be required to increase the dynamic strength. Bolt connections have provided useful as detachable connections. They make it possible, inter alia, to form a folding hinge which is used primarily in the military area.
GB-A 2 131 373 discloses a rotor blade for a main rotor of a rotary-wing aircraft, made of fibre-reinforced plastic comprising a blade section and a connecting section for fastening the rotor blade to a drive device which comprises a sleeve-shaped connecting device with flat fibre layers running substantially in the plane of extension of the connection section. An axial-radial elastomeric bearing is incorporated in the blade root for connection of the rotor blade.